A simple system for intraoperative antiseptic wound ventilation

Intra-operative tissue oxygen tension is increased by local insufflation of humidified-warm CO2 during open abdominal surgery in a rat model

INTRODUCTION

Maintenance of high tissue oxygenation (PtO2) is recommended during surgery because PtO2 is highly predictive of surgical site infection and colonic anastomotic leakage. However, surgical site perfusion is often sub-optimal, creating an obstructive hurdle for traditional, systemically applied therapies to maintain or increase surgical site PtO2. This research tested the hypothesis that insufflation of humidified-warm CO2 into the abdominal cavity would increase sub-peritoneal PtO2 during open abdominal surgery.

MATERIALS AND METHODS

15 Wistar rats underwent laparotomy under general anesthesia. Three sets of randomized cross-over experiments were conducted in which the abdominal cavity was subjected to alternating exposure to 1) humidified-warm CO2 & ambient air; 2) humidified-warm CO2 & dry-cold CO2; and 3) dry-cold CO2 & ambient air. Sub-peritoneal PtO2 and tissue temperature were measured with a polarographic oxygen probe.

RESULTS

Upon insufflation of humidified-warm CO2, PtO2 increased by 29.8 mmHg (SD 13.3; p<0.001), or 96.6% (SD 51.9), and tissue temperature by 3.0°C (SD 1.7 p<0.001), in comparison with exposure to ambient air. Smaller, but significant, increases in PtO2 were seen in experiments 2 and 3. Tissue temperature decreased upon exposure to dry-cold CO2 compared with ambient air (-1.4°C, SD 0.5, p = 0.001).

CONCLUSIONS

In a rat model, insufflation of humidified-warm CO2 into the abdominal cavity during open abdominal surgery causes an immediate and potentially clinically significant increase in PtO2. The effect is an additive result of the delivery of CO2 and avoidance of evaporative cooling via the delivery of the CO2 gas humidified at body temperature.

Can Wound Desiccation Be Averted During Cardiac Surgery? An Experimental Study

During cardiac surgery the wound is exposed to desiccation, especially as a result of operating room ventilation and the insufflation of dry carbon dioxide (CO(2)) for de-airing. We compared the gas humidity and desiccation rates in an in vitro model of a cardiothoracic wound during these conditions and during insufflation of humidified CO(2). To assess the influence of flow velocity, CO(2) was insufflated at 10 L/min via two devices, a standard open-ended tube and a low-velocity gas diffuser. The treatment arms were compared with a control without insufflation. When insufflated via the open-ended tube the humidity in the model was almost equal to the control, both with dry and humidified CO(2). However, the total desiccation rate was more rapid than the control (P < 0.001), especially in the area exposed to the gas jet where the desiccation rate was three times more rapid (P < 0.001). With the gas diffuser, dry CO(2) caused almost zero humidity and a desiccation rate that was almost equal to the control. Humidified CO(2) increased humidity in comparison with the control (P < 0.001) and decreased the desiccation rate by >90% (P < 0.001). Humidified CO(2) may be used to avert desiccation of the cardiothoracic wound. The humidified gas is effective only when delivered via a low-velocity outlet device.